It is often a requirement for liquid dispensing apparatuses to regularly clean a liquid dispensing head of the apparatus.
For example, an inkjet recording apparatus (such as an inkjet printer) may include a head cleaning unit, which may be used to clean an inkjet head so that a contamination in apparatus or tainting of recording medium, caused by dripping or scattering of ink, can be prevented or suppressed. Such inkjet recording apparatus may include an inkjet head and a wiping member, for example. The inkjet head typically has a nozzle face including nozzle hole(s) for discharging ink to a recording medium, and the wiping member may remove ink adhered on the nozzle face of the inkjet head. Such inkjet recording apparatus may also include a wiping preparation unit, a wiper-contacting unit, and a wiper-separating unit, for example. The wiping preparation unit may position the wiping member to a ready-to-wipe position, which may be offset from the nozzle face of the inkjet head by a given distance. The wiper-contacting unit may position the wiping member to a position contactable to the inkjet head from the ready-to-wipe position, set by the wiping preparation unit. The wiper-separating unit may separate the wiping member at the contacting position from the inkjet head when a wiping operation is finished.
In such inkjet printer, ink may be accumulated to one end of the inkjet head by a first wiping process and then such accumulated ink may be removed by a second wiping process, for example. In such inkjet printer, a wiping operation may be conducted two times separately. However, in such instances, a cleaning time may undesirably become longer. Further, the wiping member elastically deform to return to its original shape when the wiping member finishes the wiping operation, because the wiping member may not be in contact with the inkjet head when the wiping member finishes the wiping operation, by which ink scattering may unfavorably occur.
In another inkjet printer, ink may be wiped from a recording head while ink scattering phenomenon is suppressed.
In such inkjet printer, ink may be discharged from a nozzle array, disposed on a head, to a recording medium to form an image on the recording medium. Such inkjet printer may include a cleaning blade under the head, slanted from an alignment direction of the nozzle array. Such cleaning blade may slide on the nozzle array face, while in contact with the nozzle array face, to remove ink from the nozzle array.
Although such cleaning blade may remove ink from the nozzle array gently from the nozzle array by positioning the cleaning blade in a slanted manner, such cleaning blade is typically not configured to remove ink accumulated at one end of the nozzle array.
In another case, an inkjet recording apparatus may include a head refreshing unit using dyestuff ink for refreshing a inkjet head for discharging pigment ink. Such dyestuff ink may be used only for refreshing operation. In such inkjet recording apparatus, pigment ink may become sticky on the inkjet head or in a capping of inkjet head.
A head refreshing operation may be conducted by adding (e.g., spraying) dyestuff ink to such sticky pigment ink, to render the sticky pigment ink fluid and effectively removed from the inkjet head.
In such inkjet recording apparatus, dyestuff ink may be used to prevent or suppress degradation of nozzle array used for discharging pigment ink.
Such method may be applicable for a color printer, which may use pigment ink for black ink and dyestuff ink for other color inks (e.g., cyan, magenta, and yellow), in which a dyestuff ink of black may be provided for the above-mentioned refreshing operation.
However, an increased demand on image quality produced by color printer may shift an ink material for color inks (e.g., cyan, magenta, and yellow) from dyestuff ink to pigment ink. In such color printer, the above-mentioned method using dyestuff ink for refreshing the inkjet head discharging pigment ink may not be applicable from a viewpoint of manufacturing or maintenance cost of printer. If dyestuff color inks (e.g., cyan, magenta, and yellow) to be used for refreshing operation may be provided in a color printer, such color printer may undesirably increase its size.
In another case, an inkjet printer may have a head-wiping unit for removing ink droplet adhered on a nozzle face of ink head while suppressing ink scattering.
Such head wiping unit may include a plurality of blades arranged with a given interval between blades in a movement direction of blade. Such blades may remove ink adhered on the nozzle face of the ink head, which may move with a carriage in a given scanning direction. In such head-wiping unit, one of the blades may contact with the ink head when removing ink from the ink head.
In general, an ink removing member may contact a nozzle surface with a given contact pressure or a given deflection amount due to a contact force of the ink removing member to the nozzle surface. In other words, the ink removing member may elastically deform its shape when removing ink from a nozzle surface so that ink removing member may contact closely on the nozzle surface.
In such configuration, such ink removing member may release its elastic force at the edge of the inkjet head once an ink removing operation has finished, by which an ink scattering may occur.
Conventionally, an inkjet recording apparatus may employ dyestuff ink and inkjet-specific sheets, in which an image quality produced on inkjet-specific sheets may be maintained at a given level.
With a growing demand of a higher image quality produced on a plain sheet by an inkjet recording apparatus, recent inkjet recording apparatuses may employ pigment ink having a relatively higher viscosity to prevent or suppress bleeding phenomenon on a plain sheet.
However, pigment ink more likely sticks on an ink head or a refreshing unit of an inkjet recording apparatus, and therefore such inkjet recording apparatus may have drawbacks such as degradation of head refreshing performance in a shorter period of time.
Further, an ink scattering during a cleaning operation may become serious because a mass weight of ink has increased due to employment of pigment ink.
In some case, pigment ink may be accumulated at a wiping head, or pigment ink scattered by removing operation may stick and accumulate on a refreshing unit or nozzle face, which may lead to a malfunctioning of refreshing unit, and image quality degradation.